Uric acid metabolism in starvation

Clinical research framework proposal for ketogenic metabolic therapy in glioblastoma

Glioblastoma (GBM) is the most aggressive primary brain tumor in adults, with a universally lethal prognosis despite maximal standard therapies. Here, we present a consensus treatment protocol based on the metabolic requirements of GBM cells for the two major fermentable fuels: glucose and glutamine. Glucose is a source of carbon and ATP synthesis for tumor growth through glycolysis, while glutamine provides nitrogen, carbon, and ATP synthesis through glutaminolysis. As no tumor can grow without anabolic substrates or energy, the simultaneous targeting of glycolysis and glutaminolysis is expected to reduce the proliferation of most if not all GBM cells. Ketogenic metabolic therapy (KMT) leverages diet-drug combinations that inhibit glycolysis, glutaminolysis, and growth signaling while shifting energy metabolism to therapeutic ketosis. The glucose-ketone index (GKI) is a standardized biomarker for assessing biological compliance, ideally via real-time monitoring. KMT aims to increase substrate competition and normalize the tumor microenvironment through GKI-adjusted ketogenic diets, calorie restriction, and fasting, while also targeting glycolytic and glutaminolytic flux using specific metabolic inhibitors. Non-fermentable fuels, such as ketone bodies, fatty acids, or lactate, are comparatively less efficient in supporting the long-term bioenergetic and biosynthetic demands of cancer cell proliferation. The proposed strategy may be implemented as a synergistic metabolic priming baseline in GBM as well as other tumors driven by glycolysis and glutaminolysis, regardless of their residual mitochondrial function. Suggested best practices are provided to guide future KMT research in metabolic oncology, offering a shared, evidence-driven framework for observational and interventional studies.

Impact of a Single 36 Hours Prolonged Fasting Period in Adults With Type 1 Diabetes - A Cross-Over Controlled Trial

Prolonged fasting has shown beneficial effects in healthy individuals and in people with chronic diseases. In type 1 diabetes, the effect or even the feasibility of fasting is unclear. We aimed to assess the impact and safety of prolonged fasting in adults with type 1 diabetes. Glycemia was assessed during overnight fasting (12 hours) vs. prolonged fasting (36 hours) via an intermittently-scanned continuous glucose monitoring system. Anthropometric data, metabolic and hormonal markers were compared between both trial arms. After each fasting period, a 75 g oral glucose tolerance test was performed and plasma glucose levels and hormones were assessed. Data were compared via paired t-tests and mixed-model regressions (p ≤ 0.05). Twenty individuals with type 1 diabetes (7 females) with a mean ± SD age of 35 ± 11 years, body mass index (BMI) 24.8 ± 2.8 kg/m² and HbA_1c 54 ± 7 mmol/mol were included. Hypoglycemia/hour (70 mg/dL; <3.9 mmol/L) was similar in both trial arms (12 hrs: 0.07 ± 0.06 vs. 36 hrs: 0.05 ± 0.03, p=0.21). Glycemic excursions during the oral glucose tolerance test were not different after the two fasting periods. Beta-hydroxybutyrate levels were higher after prolonged fasting (p=0.0006). Our study showed that people with type 1 diabetes can safely perform a 36 hours fasting period with a low risk of hypoglycemia and ketoacidosis.

CLINICAL TRIAL REGISTRATION

DRKS.de, identifier DRKS00016148.

Economic Status Moderates the Association Between Early-Life Famine Exposure and Hyperuricemia in Adulthood

CONTEXT

The double burden of malnutrition (DBM), undernutrition in early life and an obesogenic environment later on, influences later risk of chronic disorders. The Great Famine in China from 1959 to1962 and remarkable economic development from the 1980s provided such a burden for a large number of people in their 60s.

OBJECTIVE

We aimed to analyze the effect of economic status on the association between famine exposure in early life and hyperuricemia in adulthood.

DESIGN AND SETTING

Participants numbering 12 666 were enrolled in China based on the Survey on Prevalence in East China for Metabolic Diseases and Risk Factors (SPECT-China) Study from 2014 to 2016.

PARTICIPANTS

Participants with fetal or childhood famine exposure (birth year 1949-1962) formed the exposure group.

MAIN OUTCOME MEASURE

Hyperuricemia was defined as uric acid (UA) > 420 μmol/L for men and > 360 μmol/L for women. The association of famine with hyperuricemia was assessed via regression analyses.

RESULTS

Early-life famine exposure was negatively associated with UA levels (P = .045) but was not associated with hyperuricemia (P = .226) in the whole study population. Economic status could moderate the association of famine exposure with UA and hyperuricemia (P ≤ .001). In participants with high economic status, early-life famine exposure was positively associated with UA levels (unstandardized coefficients 7.61, 95% CI 3.63-11.59, P < .001), and with hyperuricemia (odds ratio 1.47, 95% CI 1.19-1.81, P < .001).

CONCLUSIONS

Economic status could moderate the association between exposure to famine in early life and hyperuricemia in adulthood, indicating that the DBM might affect hyperuricemia in an opposite direction of the effects of undernutrition in early life alone.

Early-life exposure to the Chinese famine of 1959-61 and risk of Hyperuricemia: results from the China health and retirement longitudinal study

Background

Short-term starvation has been related to hyperuricemia. However, little is known about the long-term effect of early-life exposure to famine on hyperuricemia risk in adulthood.

Methods

The analysis included 2383 participants from the China Health and Retirement Longitudinal Study in 2015. Hyperuricemia was diagnosed as serum uric acid ≥7 mg/dL in men and serum uric acid ≥6 mg/dL in women. Famine exposure subgroups were defined as unexposed (born between October 1, 1962, and September 30, 1964), fetal-exposed (born between October 1, 1959, and September 30, 1961), and early-childhood exposed (born between October 1, 1956, and September 1, 1958). The association between early-life famine exposure and hyperuricemia risk was assessed using multivariate logistic regression.

Results

The prevalence of hyperuricemia in the unexposed, fetal-exposed, and early-childhood exposed participants was 10.7, 14.1, 11.1%, respectively. Compared with unexposed and early-childhood exposed participants combined as an age-balanced control, fetal-exposed participants showed an increased risk of hyperuricemia in adulthood (OR = 1.41; 95% CI: 1.06–1.88), after adjusting for gender, marital status, famine severity, residence, smoking, drinking, BMI, hypertension, and diabetes. The famine effect on hyperuricemia was accentuated by overweight or obesity (P for interaction = 0.042). Compared with unexposed and BMI < 24 kg/m² participants, the OR (95%CI) of hyperuricemia was 3.66 (2.13–6.30) for fetal-exposed and overweight/obesity participants. However, combined unexposed and early-childhood exposed participants as an age-balanced control, the interaction of famine exposure and BMI was not statistically significant (P for interaction = 0.054).

Conclusion

Famine exposure in the fetal stage was associated with an increased risk of hyperuricemia in adulthood.

Use of the uricase-inhibited rat as an animal model in toxicology

An accessible, reproducible, and inexpensive animal model for toxicologic evaluation of hyperuricemic conditions has been required for some time. A number of authors have tried to develop such a model by administering high doses of uric acid to various animal species (dog, rabbit, rat) but the potent liver uricase in these species prevented development of sustained hyperuricemia. Johnson et al. [4], Stavric et al. [5], and a number of other investigators [72, 75] successfully used potassium oxonate [63] to block the effect of hepatic uricase and to produce hyperuricemia in rats [4, 5, 68, 69, 72, 74, 76, 80], rabbits [66], mongrel dogs [67], mice [65], and pigs [64]. The oxonate-treated rat can serve as a useful animal model not only in investigation of the uric acid nephropathy, but also in a number of other toxicologic evaluations connected with uric acid. This model has been used to evaluate drugs that affect uric acid excretion, to determine which dietary factors affect serum urates, or to evaluate possible therapeutic agents in certain disorders associated with uric acid. The same model could also be used by behavioral scientists, for whom research on uric acid has become increasingly popular in recent years [33, 137]. The ideal uricase inhibitor for induction of hyperuricemia would be one which is irreversible, noncompetitive, and relatively nontoxic, so that its activity would be independent of high levels of uric acid, and effective inhibition could be attained at low dosage levels. Oxonic acid is not an ideal uricase inhibitor, because it is competitive and is eliminated from the body relatively rapidly. Although relatively nontoxic, oxonic acid and its salts are foreign substances that could interfere with some other metabolic systems. The possibility exists that an ideal, or at least a better inhibitor, could be developed by appropriate substitutions on the molecule of oxonic acid or by introducing different types of compounds such as derivatives of diazohypoxanthines, barbiturates, or similar substances. Until such improvements on the uricase-inhibited rat models are available, potassium oxonate, which is easily obtainable, can be used as an effective inhibitor of uricase in vivo.

A multi-disciplinary catalogue of uric acid literature of interest to behavioural scientists

The research on uric acid encompasses a large number of disciplines and their respective journals. This bibliography (1948 to 1972) was assembled to provide a co-ordinated reference to this source material for behavioural scientists.